Childhood and adolescent obesity tracks into adulthood. Data show that it is likely obese children will become obese adults. The relationship between obesity and sedentary behavior appears overwhelming. Virtually no age group, gender, or ethnicity meets the recommended amount of physical activity suggested by the CDC/ACSM guidelines or the guidelines shown in Healthy People 2010. School curriculums promote sedentary behavior as the vast majority use instructional strategies that restrict or prohibit appreciable movement. Thus, a vast opportunity is present within schools to increase physical activity. To diminish childhood obesity, we intend to emphasize physical activity accumulated intermittently throughout the school day, taught by regular classroom teachers, and delivered through standard academic lessons. We call this approach "Physical Activity Across the Curriculum," or PAAC. Our primary outcome measurement is body mass index as this is now recommended by major health organizations as the preferred measure for the determination of obesity. In elementary school children, we will determine if 3 years of increased physical activity will diminish gains in body mass index (BMI). We will use classroom teachers and the established academic curriculum to deliver appropriate, moderate intensity, intermittent, physically active, academic lessons with a minimal accumulation of 90 minutes per week. Specifically, we expect that children receiving PAAC will show a lesser BMI after 3 years of PAAC when compared to children receiving standard physical education classes only. We have a number of secondary aims that are important themselves and will increase our understanding of any differences in BMI observed between those children that receive PAAC and those children that do not receive PAAC. 1) We expect children that receive PAAC will have improved levels of lipids, glucose, insulin and blood pressure compared to those children that do not receive PAAC. We expect this to be most evident in those children that show elevated baseline values. 2) We expect children receiving PAAC to show similar or greater physical activity outside of school after 3 years of PAAC compared to children receiving standard physical education classes only. 3) We will conduct a process evaluation and will evaluate academic achievement to determine the extent that PAAC was implemented as designed and the impact of PAAC on learning. We believe that 90 additional minutes of moderate intensity, intermittent, physical activity (PAAC) will be sufficient to attenuate increases in BMI compared to controls who do not receive PAAC. Additionally, PAAC will offer a strategy to increase physical activity during the school day that is complimentary to academics and does not diminish or compete for the time allocated for academic instruction.